1. Field of the Invention
The present invention relates to an adhesive sheet having anti-static properties. More specifically, the present invention relates to an anti-static adhesive sheet that has a substrate and an adhesive layer on one or both surfaces of the substrate.
2. Description of the Related Art
In the cutting or grinding process for semiconductor wafers, an adhesive sheet for semiconductor wafer working that is composed of an adhesive layer and a substrate film is conventionally adhered to a semiconductor wafer so as to hold the semiconductor wafer or to protect the circuit surface thereof. Prior to adhering to the semiconductor wafer, when a release sheet is peeled off from the adhesive sheet for semiconductor working, static electricity is generated, and the resulting electrically charged adhesive sheet for semiconductor working is adhered to the semiconductor wafer. In addition, after the above process, when the adhesive sheet for semiconductor wafer working is peeled off from the semiconductor wafer, static electricity is also generated, and the static electricity has caused problems of damaging circuits and others.
To address the above problems, Japanese Patent Laid-Open Publication No. 2000-212535 discloses an adhesive sheet that is obtained by coating a pressure-sensitive anti-static adhesive of an alkyl(meth)acrylate-based copolymer having at least one quaternary ammonium/organic acid salt group as a side chain.
Japanese Patent Laid-Open Publication No. 2000-183140 discloses a sheet for holding semiconductor wafers, in which a photocurable anti-static layer containing a base polymer, a photocurable compound, an anti-static agent and a photoinitiator is formed between a substrate sheet and an adhesive layer, and the photocurable anti-static layer is formed into three-dimensional network structure by UV-ray irradiation. As the anti-static agent, polyethyleneglycol and alkylolamide are used.
Japanese Patent Laid-Open Publication No. 2005-23188 discloses an adhesive for a dicing adhesive sheet containing a base polymer, a radiation curable compound having 5 or more carbon-carbon double bonds in the molecule, and a low molecular weight component having from 1 to 4 carbon-carbon double bonds in the molecule and a molecular weight of from 100 to 1,000. As the above low molecular weight component, polyalkyleneglycol(meth)acrylate or polyalkyleneglycol di(meth)acrylate is used.